Viper 60s Theory Of Operation And Maintenance Manual page 157

VIPER SCSI 60, 125 & 150 THEORY OF OPERATION AND MAINTENANCE
6.9 Data Cartridge
The data cartridge
is
an enclosed, self-contained mechanism that provides access to the tape
surface by the drive heads and transports the tape across the head. The following are
descriptions of the cartridge components shown in Figure 6-12.
Table 6·5. Data Cartridge Components
Baseplate
Tape Guides
and Wrap Pins
Write Protect plug
and Access Door
Tape and Tape Hubs
Holes
Beginning Of Tape (BOT)
End Of Tape (EaT)
Load Point (LP)
Early Warning (EW)
Mirror
The baseplate provides the structure and stability for the data cartridge. It
also is the mounting platform for all internal components of the drive and
defines the mounting plane to locate the cartridge within the drive.
Two tape guides located on each side of the door opening, control the
wrap angle of the tape around the recording head.
The wrap pins control the wrap angle of the tape to reduce tension
variations as the tape moves from one end to the other.
The write protect plug is a capped, hollow cylinder with half of the wall
removed. Depending upon the position of this cylinder the write head is
either disabled or enabled so data on the tape cannot be overwritten.
The tape and transport mechanism are protected by a clear plastic case
which contains an access door that is automatically opened by the tape
drive as the cartridge is inserted to allow access to the tape by the read!
write heads.
The tape is wound (magnetic side out) onto two hubs that act alternately as
or take on direction.
A number of precisely located holes are found near each end of the tape.
These holes are detected by the drive sensor assembly which generates
hole-detect signals used to control tape motion. The tape holes are
Three upper and lower hole pairs,indicating the Beginning-Of-Tape
three lower holes indicating the End-Of-Tape position.
one upper hole near BOT indicating the start of recorded data.
one upper hole near EaT indicating the end of the tape is near.
Notice that the distance between BOT and LP holes is 36 inches
DC300XLP cartridge, 48 inches for the DC600A cartridge, and 60
for the DC600XTD cartridge. The Viper tape drive differentiates
ht:>ruJt:>t:>n
data cartridge types by recognizing these distances.
The mirror is part of an optical sensing system. It reflects light through pre-
punched holes toward the back of the drive to alert the drive when
recording area limits are reached.
6-26